Method for manufacturing objects using powder products

ABSTRACT

A method for manufacturing a three-dimensional part. The method includes: performing partial densification processing on loose machining powder, to form a densified and sealed enclosure, where there is still loose machining powder accommodated inside the enclosure; and performing overall densification processing on the enclosure and the machining powder inside the enclosure, so as to implement metallurgical bonding between the machining powder inside the enclosure and the enclosure during the densification, thereby forming a target three-dimensional part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority under 35 USC 119 toearlier-filed China Patent Application 201410065130.3, filed Feb. 25,2014, which is hereby incorporated by reference.

TECHNICAL FIELD

Embodiments of the technology relate generally to manufacturing methods,and in particular, to a three-dimensional object manufacturing methodusing powder products.

BACKGROUND

For the production of complex and high performance articles, powdermetallurgical processing has been used and often provides significantadvantages over other casting and wrought processing routes. Multipletechniques have been developed to process powder or particulatematerials into bulk essentially fully dense articles including pressingand sintering, canning and densification, and additive manufacturing. Ineach of these techniques, the complexity and production cost of theprocessing must be considered in defining effective routes forproduction of articles. Cost of the raw material and amount of machiningor shaping processing after densification can also significantly affectthe selection of optimized processing routes. Processing route may alsoaffect the resulting physical, microstructural, and mechanicalproperties of the article and so article performance level also may beconsidered in defining the process route. In order to produce complexand high performance articles, several typical techniques are known inthe art.

For complex shaped articles, additive manufacturing processes have beenused which have the capability of producing net or near net shapesdirectly. Electron beam melting (EBM) and direct metal laser melting(DMLM) are examples of types of additive manufacturing for threedimensional articles, especially for metal objects. They are oftenclassified as rapid manufacturing methods because they also have theadvantage of being able to produce a part from an electronic definitionwithout the need to produce specialized tooling which can often lead tolong lead times for production of articles by other processing routes.Many of the additive processing technologies including EBM and DMLMtechnologies manufacture three-dimensional objects by melting powderlayer by layer with a laser beam or an electron beam in a high vacuumchamber in the case of EBM, and in a chamber, typically under inert gasfor DMLM. For example, an EBM or DMLM machine reads data from athree-dimensional model and lays down successive layers of powderedmaterial according to the three-dimensional model. These layers ofpowdered material are melted together by utilizing a computer controlledelectron or laser beam. In this way it builds up the three-dimensionalobject to be manufactured. The process takes place under vacuum for EBM,while DMLM may be performed under vacuum or inert gas, such as Argon,which makes it suited to manufacture three-dimensional objects ofreactive materials with a high affinity for oxygen, e.g. titanium. Thesetechniques are particularly well suited for producing limited numbers ofparts at low or intermediate volumes due to the typical deposition ratesused. However, when the number of the three-dimensional objects to bemanufactured is quite large, the whole manufacturing process may takemuch more time. This will require more EBM and/or DMLM machines to beused to meet the throughput which will increase the investment.

For more simple shaped and larger articles, canning and densificationprocessing of powders is also used. With these powder metallurgicalprocesses, materials are typically placed into a can that isolates thematerials from the surrounding environment and provides a transfermedium for further processes, such as hot isostatic pressing (HIP) andpneumatic isostatic forging (PIF). Cans are typically fabricated fromsheet materials and welded into the shape of interest to make anarticle. Cans are oversized versus the desired final product size andshape in order to account for shrinkage than occurs duringdensification. Cans can be filled with loose powder or may be used toencapsulate pressed or semi porous powder preforms. Cans provide amanner in which the powder materials may be mechanically pressed into aporous or semi-porous object which is suitable for handling, transfer,and consolidation or densification into a target object. However, theuse of the can requires several extra steps and leads to higher yieldloss (due in part to interaction between the materials and the canmaterial), thus reducing efficiency and increasing cost. Can cost andcomplexity can contribute significantly to the overall cost and timeneeded to produce powder articles or objects.

Whether processed by additive manufacturing processes or by canning ofloose partially densified compacts, powder derived materials arefrequently subjected to densification processes that utilize elevatedtemperature, pressures, or both, in order to fully densify thestructure. Some examples of such processing include sintering, hotpressing, and hot isostatic pressing (HIP). Additionally, U.S. Pat. No.5,816,090 discloses a process for the consolidation of powder objectsusing pneumatic isostatic forging (PIF). Rather than applying heat andpressure simultaneously over a longer period of time, as in the typicalHIP process, the '090 patent relies on high temperatures and higherpressures over a short period of time in a pneumatic isostatic forgingprocess. The '090 patent describes only partially sealing the outersurface of the workpiece, or coating the workpiece with a potentiallyreactive material, prior to the “pre-sintering” step disclosed therein.The '090 patent therefore discloses solutions that apply only to theprocess described therein and relies on extra steps not used in typicalHIP processes.

Pressing and sintering processes are also used whereby powders are putinto a die and pressed into a shape, released from the die and thensintered at high temperatures in order to densify by diffusion. In thisprocessing route, higher part volumes may be feasible but resultingarticles are typically limited in geometry and ultimate density leveland may be inferior to other powder metallurgical processing routes.

Frequently powder metallurgical processing is used in order to producehigh performance materials with properties that are difficult orimpossible to achieve using standard casting and wrought processingmethods. Processing routes that involve solid state processing (pressand sinter, or can and densify, for example) may be advantageous overfusion based additive processing routes in that fine scalemicrostructural features may be maintained through processing and nosolidification type structures may be produced during processing. Suchconstraints can also make optimum processing difficult for complex highperformance materials.

For these and other reasons, there is a need for increasing efficiencyand saving cost in the rapid manufacturing field, and in particular, indensification processes involving powder metallurgy processing andsubsequent densification by processes such as HIP and/or PIF.

SUMMARY

One or more aspects are summarized in the present invention tofacilitate a basic understanding of the present invention, where theinduction of the present invention do not extend the overview, and isneither intended to identify certain elements of the present invention,nor intended to draw out of its range. On the contrary, the main purposeof the induction is to present some concepts of the present invention ina simplified form before more detailed descriptions are presented below.

An aspect of the present invention is to provide a method formanufacturing a three-dimensional part. The method includes: performingpartial densification processing on loose machining powder, to form adensified and sealed enclosure, where there is still loose machiningpowder accommodated inside the enclosure; and performing overalldensification processing on the enclosure and the machining powderinside the enclosure, so as to implement metallurgical bonding betweenthe machining powder inside the enclosure and the enclosure during thedensification, thereby forming a target three-dimensional part.

Another aspect of the present invention is to provide another method formanufacturing a three-dimensional part. The method includes: performingpartial densification processing on loose machining powder by using anEBM technology, to form a densified and sealed vacuum enclosure, wherethere is still loose machining powder accommodated inside the enclosure;repeating the foregoing step until a predetermined number of theenclosures that accommodate the loose machining powder are machined; andperforming overall densification processing simultaneously on thepredetermined number of the enclosures that accommodate the loosemachining powder, so as to implement metallurgical bonding between themachining powder inside the several enclosures and a correspondingenclosure during the densification, thereby simultaneously forming thepredetermined number of target three-dimensional parts.

Yet another aspect of the present invention is to provide another methodfor manufacturing a three-dimensional part. The method includes:performing partial densification processing on loose machining powder byusing an additive manufacturing technology, to form a densifiedenclosure with an airway tube, where there is still loose machiningpowder accommodated inside the enclosure; connecting the airway tube toan air-extracting apparatus to discharge gas from the enclosure;performing sealing processing on the enclosure after a vacuum degreeinside the enclosure reaches a predetermined value; repeating theforegoing step until a predetermined number of sealed vacuum enclosuresthat accommodate the loose machining powder are machined; and performingoverall densification processing simultaneously on the predeterminednumber of the enclosures that accommodate the loose machining powder, soas to implement metallurgical bonding between the machining powderinside the several enclosures and a corresponding enclosure during thedensification, thereby simultaneously forming the predetermined numberof target three-dimensional parts.

Yet another aspect of the present invention is to provide another methodfor manufacturing a three-dimensional part. The method includes:performing first densification processing on loose machining powder, toform a permeable porous half-finished part having a first density level;performing second densification processing on an outer surface area ofthe half-finished part, to form the outer surface area into a sealedenclosure having a second density level; and performing overalldensification processing on the outer surface area having the seconddensity level and an inner area having the first density level, to forma target three-dimensional part.

Compared with the prior art, in the present invention, athree-dimensional part is manufactured and machined in steps. First,selective enclosure machining is performed on loose machining powder byusing, for example, an additive manufacturing technology. In this way,in a situation in which a large quantity of target parts are to bemachined, efficiency is significantly improved and energy consumption issignificantly reduced because only an enclosure section, which occupiesa very small portion of the entire part, is machined in the step. Then,in a subsequent step of an HIP or PIF technology, overall densificationprocessing is performed simultaneously on the foregoing numerousenclosures that are finished machining and accommodate machining powder,so as to machine numerous target three-dimensional parts at once.Because numerous half-finished parts are machined simultaneously at oncein the step, efficiency is also improved, and energy consumption is alsoreduced. In addition, metallurgical bonding between the enclosure andthe machining powder inside the enclosure is implemented in the stepwithout applying a conventional can to aid the machining. In this way, amanufacturing technique is significantly simplified.

BRIEF DESCRIPTION

These and other features, aspects, and advantages of the presenttechnology will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic view of an exemplary EBM machine for manufacturinga shell containing powder of a target object;

FIG. 2A, FIG. 2B, FIG. 2C, and FIG. 2D are schematic views of differentmanufacturing statuses of the shell of the target object manufactured bythe EBM machine of FIG. 1;

FIG. 3A, FIG. 3B, FIG. 3C, FIG. 3D, FIG. 3E, and FIG. 3F are schematicviews of different manufacturing statuses of the shell of the targetobject manufactured by the EBM machine of FIG. 1 in another aspect;

FIG. 4 is a schematic view of an exemplary HIP machine for manufacturingthe shell containing powder of the target object manufactured by the EBMmachine of FIG. 1 in a beginning status;

FIG. 5 is a schematic view of an exemplary HIP machine for manufacturingthe shell containing powder of the target object manufactured by the EBMmachine of FIG. 1 in a finished status;

FIG. 6 is a flowchart of a method for manufacturing a three-dimensionalobject, according to one embodiment;

FIG. 7 is a schematic view of an original three-dimensional model and acompensated three-dimensional model according to an implementationmanner of the invention;

FIG. 8A, FIG. 8B, FIG. 8C, and FIG. 8D, and FIG. 9A, FIG. 9B, and FIG.9C are two schematic views of different manufacturing statuses of ashell containing powder of a target object manufactured by an SLM methodaccording to an implementation manner of the invention;

FIG. 10 is a schematic view of an exemplary HIP machine formanufacturing the shell containing powder of the targetthree-dimensional object manufactured by the Selective Laser Melting(SLM) method of FIGS. 8A-8D and 9A-9C in a beginning status;

FIG. 11 is a schematic view of a process to cut a duct part from atarget object according to an implementation manner of the invention;

FIG. 12 is a schematic view of a shell containing powder of a targetobject, according to another embodiment;

FIG. 13 is a flowchart of a method for manufacturing a target object,according to another embodiment;

FIG. 14 is a schematic view of a shell containing powder of a targetobject, according to yet another embodiment;

FIG. 15 is a schematic view of a shell containing powder of a targetobject, according to yet another embodiment;

FIG. 16 is a schematic view of a shell containing powder of a targetobject, according to yet another embodiment;

FIG. 17 shows several stages of a method for forming a target object;and

FIG. 18 shows several stages of an alternative embodiment of a methodfor forming a target object.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described with referenceto the accompanying drawings. In the subsequent description, well-knownfunctions or constructions are not described in detail to avoidobscuring the disclosure in unnecessary detail.

Unless defined otherwise, technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art to which this invention belongs. The terms “first”, “second”,and the like, as used herein do not denote any order, quantity, orimportance, but rather are used to distinguish one element from another.Also, the terms “a” and “an” do not denote a limitation of quantity, butrather denote the presence of at least one of the referenced items, andterms such as “front”, “back”, “bottom”, and/or “top”, unless otherwisenoted, are merely used for convenience of description, and are notlimited to any one position or spatial orientation. Moreover, the terms“coupled” and “connected” are not intended to distinguish between adirect or indirect coupling/connection between two components. Rather,such components may be directly or indirectly coupled/connected unlessotherwise indicated.

Referring to FIG. 1, an exemplary EBM machine 10 for manufacturingthree-dimensional objects is shown. For ease of explanation, onlycertain parts of the EBM machine 10 are shown in FIG. 1. As an example,the EBM machine 10 includes an electron beam gun 11, a vacuum chamber12, a building table 13, a powder container 14, and a controller 15. Inother embodiments, the EBM machine 10 may have other differentconfigurations. Moreover, rather than utilizing an EBM machine,alternative embodiments may utilize any possible manner of emittingenergy or heat, including, but not limited to, direct metal lasermelting, laser sintering, and infrared.

The electron beam gun 11 is used to generate an electron beam 112 tomelt powder 142 located on the building table 13 layer by layeraccording to a three-dimensional model stored in the controller 15, tobuild a target three-dimensional object which has the same shape as thethree-dimensional model. The powder container 14 is used to contain thepowder 142 and deliver the powder 142 onto the building table 13 layerby layer according to control signals from the controller 15. Thecontroller 15 controls the electron beam gun 11, the vacuum chamber 12,the building table 13, and the powder container 14 according topredetermined control programs, and the whole manufacturing process isunder vacuum environment in the vacuum chamber 12. It is understood thatthe EBM machine 10 may include other additive parts, such as powersupplies, communication interfaces, etc.

Referring to FIGS. 1, 2 and 3 together, some different manufacturingstatuses of a shell 24 containing the powder 142 of a target object 20manufactured by the EBM machine 10 is shown. For ease of explanation, atarget object 20 shown in FIG. 5 is a columnar solid element. In otherembodiments, the shape of the target object 20 may vary according todifferent requirements. The target object 20 shown in FIGS. 2 and 3 isan unfinished target object 20. In FIGS. 2 and 3, the shell 24 of thetarget object 20 is not exactly columnar-shape because the shell 24needs to be compensated in this EBM manufacturing process before thesubsequent HIP manufacturing process. After HIPping the shell 24containing powder 142 manufactured by the EBM machine 10, the targetobject 20 may be manufactured to the expected columnar-shape, which willbe described in the following paragraphs.

In a beginning status FIG. 2A, a first layer of the powder 142 isdelivered onto a building platform 132 of the building table 13, forexample by using a roller 134 to smoothly push the powder 142 onto thebuilding platform 132. After the first layer of the powder 142 is laidon the building platform 132 evenly, a bottom surface 21 of the shell 24is manufactured by using the electron beam 112 to melt the correspondingpart of the first layer of the powder 142 according to thethree-dimensional model, as shown in the status of FIG. 2B, and alsoshown in the status of FIG. 3A.

After the bottom surface 21 of the shell 24 is finished, a side surface22 of the shell 24 is manufactured by using the electron beam 112 tomelt the corresponding part of subsequent powder 142 layer by layeraccording to the three-dimensional model. As shown in the status of FIG.3B, a second layer of the powder 142 is put onto the building platform132, and a first layer of the side surface 22 is manufactured by usingthe electron beam 112 to melt the corresponding part of the second layerof the powder 142 according to the three-dimensional model as shown inthe status of FIG. 3C. The remaining layers of the side surface 22 areformed by the same manufacturing method as the first layer, and are notdescribed in any further detail. The status of FIG. 2C and the status ofFIG. 3D both show an intermediate status which is to manufacture onelayer of the side surface 22.

After the side surface 22 is finished, a top surface 23 of the shell 24is manufactured by using the electron beam 112 to melt the correspondingpart of last layer of the powder 142 according to the three-dimensionalmodel. As shown in the status of FIG. 2D and the status of FIG. 3E, thelast layer of the powder 142 is laid onto the building platform 132 andthen the top surface 23 is manufactured by using the electron beam 112to melt the corresponding part of the last layer of the powder 142according to the three-dimensional model. Finally, a whole shell 24 isfinished and it also contains loose powder 142, or a mixture of loosepowder and rapidly sintered supported patterns inside, as described inmore detail below. In other words, after the EBM manufacturing, thetarget object 20 including the shell 24 and the powder 142 inside of theshell 24 as shown in the status of FIG. 3F is finished. The loose powder142 may also be sintered using a faster scanning speed to below apredetermined density, for example 80%. The shell 24 is thus formed as avacuum sealed three-dimensional shell having a predetermined internalporosity.

Compared to the target object 20, the shell 24 is not finished yet andhas at least one unfinished part containing loose powder 142 or amixture of loose powder and rapidly sintered supporting patterns whichwill be manufactured by a further manufacturing method. Here, the targetobject 20 is further manufactured by HIPping as described below.However, in other embodiments, the treatment and densification processmay be other than HIP. For example, PIF or another densification processmay be utilized.

Referring to FIG. 4, the shell 24 is put into a high pressurecontainment vessel 42 of a HIP machine 40. The HIP machine 40 mayfurther include a controller 44 used to control temperature and pressureinside of the vessel 42, which can provide a HIPping force to the shell24 full of powder 142 and any supporting patterns that may be present.It is understood that the HIP machine 40 may include other additiveparts, such as power supplies, communication interfaces, etc.

In a beginning status shown in FIG. 4, the shape of the shell 24 stillmaintains the compensated shape, which is bigger than the expected shapeof the target object 20. According to predetermined program, thecontroller 44 will control the temperature and pressure in the vessel42, to provide a HIP treatment to the shell 24. During the HIP treatmentprocess, the shell 24 will press the loose powder 142 and any supportingpatterns present to make it solid and metallurgically bond with theshell 24. After finishing the HIP treatment, a solid target object 20 ismanufactured as shown in FIG. 5. In FIG. 5, the powder 142 has becomethe same or nearly the same density as the shell 24, which means theshell 24 and the loose powder 142 and any supporting patterns become onetarget object 20 to be manufactured, and the shape of the target object20 becomes the expected columnar-shape as an example.

Referring to FIG. 6, a flowchart of a method 60 for manufacturing thetarget three-dimensional object 20, according to one embodiment isshown. The method 60 begins in step 61, an original three-dimensionalmodel is input/stored preferably into the controller of an EBM machine.The original three-dimensional model is the same as the target object20. For example, FIG. 7 shows an original three-dimensional model X1which is columnar-shaped. In some embodiments, the three-dimensionalmodel is a three-dimensional computer aided design (CAD) model.

In step 62, the original three-dimensional model X1 is analyzed todetermine what the shrinkage/distortion change 29 would be after a shell28 containing loose powder having the same shape as the originalthree-dimensional model X1 is treated by the HIP process. It isunderstood that the analysis of the shrinkage change of the shellcontaining powder can be simulated and analyzed based on appropriatealgorithms, such as by using a finite element method (FEM) tool of ANSYSsoftware. The detailed analysis process is not disclosed here.

In step 63, according to above shrinkage change analysis result, acompensated three-dimensional model is calculated based on appropriatealgorithms, such as also by using the ANSYS software. For example, FIG.7 shows a compensated three-dimensional model X2 which is bigger thanthe columnar-shaped original three-dimensional model X1.

In step 64, the compensated three-dimensional model X2 is analyzed todetermine if a shell containing powder having the same shape of thecompensated three-dimensional model X2 will be changed to the same shapeas the original three-dimensional model X1 after being treated by theHIP process. If yes, the process goes to next step 65. If no, theprocess goes back the previous step 63. It is also understood that thisanalysis can be simulated based on appropriate algorithms, such as byusing the FEM tool of ANSYS software, which are not described here. Itis also understood that, in this and other embodiments, the powder sizedistribution is a key factor affecting packing density and subsequentshrinkage. Preferably the analysis in steps 61-64 are incorporated intothe controller of the EBM machine. Alternately the analysis in steps61-64 may be performed in a separate system then the output transferredto the controller for the subsequent steps 65 and on.

In step 65, a shell 24 full of loose powder 142 and any additionalsupporting patterns is manufactured by using the EBM method based on thecompensated three-dimensional model X2, which has been described above.

In step 66, the shell 24 containing the loose powder 142 and anysupporting patterns is formed into the target three-dimensional object20 by using the HIP method, which also has been described above.

According to above method 60, a target object 20 (for example shown inFIG. 5) is manufactured by combining the EBM method and the HIP process.As only the shell 24 is manufactured by the EBM process, and not thewhole target object 20, the power used by the electron beam 112 isreduced and time may be saved as well. If several target objects 20 needto be manufactured, those corresponding shells 24 with the loose powder142 and any supporting patterns can be HIP treated in the vessel 42 atthe same time, which can increase efficiency. Furthermore, the shell 24will become one part of the target object 20 through metallurgicalbonding with the powder 142 after the HIP treatment, which can furthersimplify the manufacturing process.

In other embodiments, instead of using the EBM method, the shell 24together with loose powder 142 and any supporting patterns can bemanufactured by other rapid manufacturing methods, such as selectivelaser melting (SLM) and direct metal laser melting (DMLM) methods underthe non-vacuum condition, which are respectively performed in a SLMmachine and a DMLM machine. Notably, however, both SLM and DMLM can alsobe performed under vacuum.

Referring to FIGS. 8A-8D and FIGS. 9A-9C, two schematic views forshowing different manufacturing statuses of the shell 24 manufactured bythe SLM method is shown. Compared with the EBM method shown in FIG.2A-FIG. 2D, the SLM method of FIG. 8A, FIG. 8B, FIG. 8C, and FIG. 8D maybe performed in non-vacuum condition. Furthermore, the SLM method mayfurther manufacture a duct 25 that may extend from the top surface 23.In other embodiments, the duct 25 may extend from the side surface 22.

Referring to FIG. 9A, FIG. 9B, and FIG. 9C, after the shell 24 includingthe duct 25 and containing the loose powder 142 and any supportingpatterns is finished, an air pump (not shown) is used to pump air and/orremnant inert gas from the shell 24 through a pipe 90 communicated withthe duct 25, which make the inside space of the shell 24 is vacuum (seeFIG. 9A). In some embodiments, the duct 25 is quite long or the pipe 90is quite long along the vertical direction, thus the loose powder 142cannot be removed out from the shell 24. In some embodiments, the shell24 can be placed in a big vessel having an outlet (not shown), then theair pump is used to pump air from the big vessel through the outlet,thus the air inside of the shell 24 is indirectly pumped out withoutremoving the loose powder 142. The air inside of the shell 24 can alsobe pumped out according to other modes.

When a vacuum level of the inside space of the shell 24 is satisfiedaccording to a predetermined value, for example when the vacuum level islower than about 0.01 Pascal, the extended duct 25 is sealed throughappropriated methods, such as by an appropriated welding method (seeFIG. 9B). Namely, the inside space of the shell 24 is sealed by a weldpart 29. Then, the weld part 29 is cut through appropriated cuttingmethods (see FIG. 9C), which makes the shell 24 be vacuum, like theshell 24 shown in FIG. 4. Note, the pipe may be locally heated andcrimped shut, thus ensuring the vacuum is maintained inside the shell24. The pipe may be cut above the line of the crimp.

Referring to FIG. 10, the sealed shell 24 full of loose powder 142 andany supporting patterns is treated by the HIP machine 40 to form thetarget object 20. The manufacturing process is similar to that shown inFIG. 4, and thus the process is not described again.

Referring to FIG. 11, after the HIP process, a solid target object 20 isformed, but a duct part 26, due to the duct 25, is an additional part onthe target object 20. The duct part 26 can be cut by appropriate cuttingmethods, for example a hydraulic cutting method, etc. After cutting theduct part 26, the target object 20 is finished. Similar to the EBMmethod combining the HIP method, the SLM method combining the HIP methodalso can achieve a target object 20 which metallurgically bonds theshell 24 and the powder 142. For clarity the deposition processes suchas DMLM, SLM, and EBM can be practiced with or without the duct withinthe scope of this invention.

In above mentioned embodiments, only the outside shell 24 is finishedduring the EBM or SLM process. However, in other embodiments, some ofthe powder 142 inside of the shell 24 also can be melted or sinteredinto different density levels. In that regard, referring to FIG. 12, ashell 24 of a target object 20 containing loose powder or partiallyconsolidated powder 142 according to another embodiment is shown.Compared with the shell 24 shown in FIG. 4, the shell 24 of FIG. 12 isnot a uniform solid shell but includes at least two different densitylevel layers. As an exemplary embodiment shown in FIG. 12, theillustrated shell 24 includes three different density level layers 241,242, and 243 from outside to inside. The density level from layer 241 to243 is gradually reduced. For example, the density level of the firstlayer 241 is about 100%, the density level of the target object, thesecond layer 242 is about 90%, and the density level of the third layer243 is about 80%. In other embodiments, the number of the density levellayers, the density level of each layer, the thickness of each layer canbe adjusted based on appropriate algorithms, such as by using the FEMtool of ANSYS software, which are not described here.

Referring to FIG. 13, a flowchart of a method 70 for manufacturing athree-dimensional object, according to another embodiment is shown.Compared with the method 60, the steps 71-73 of the method 70 are thesame as the steps 61-63 of the method 60. Thus, the steps 71-73 are notdescribed here.

In step 74, based on the compensated three-dimensional model, the shell24 is calculated to determine the number of the density level layers(like the layers 241, 242, 243) of the shell 24, the density level ofeach layer, and the thickness of each layer. As mentioned above, thoseparameters can be calculated based on appropriate algorithms, such as byusing the FEM tool of ANSYS software, which are not described here.

In step 75, the compensated three-dimensional model is analyzed todetermine if a shell containing powder and any supporting patternshaving the same shape of the compensated three-dimensional model will bechanged to the same shape as the original three-dimensional model afterbeing treated by the HIP process. If yes, the process goes to next step76. If no, the process goes back the previous step 73. This step 75 issimilar to the step 64 mentioned above.

In step 76, the shell 24 containing loose powder 142 and any supportingpatterns is manufactured by using the EBM method. As the shell 24includes at least two different density level layers, the electron beam112 will melt the different density level layers by using differentpower levels of electron beams according to above calculated parametersof the shell 24. Even though the shell 24 shown in FIG. 12 is thickerthan the shell 24 shown in FIG. 4, the power used by the electron beam112 is still reduced and can save time compared with the conventionalEBM methods.

In step 77, the shell 24 containing loose powder 142 and any supportingpatterns is manufactured by using the HIP method. After the HIP process,a target solid object 20 (like the object 20 shown in FIG. 5) isfinished. Because the shell 24 is manufactured to several differentdensity level layers during the EBM process, the HIP process may moreeasily and effectively achieve the target solid object 20 compared withthe method 60.

In other embodiments, the shape of the object 20 may be not regular,such as a tear drop shape. FIG. 14 shows a target object 20 as anexample. In the EBM process, the object 20 of FIG. 14 can bemanufactured from a shell like the shell 24 shown in FIG. 4, i.e. from ashell of a single density. It should be appreciated that the targetobject 20 of FIG. 14 can also be manufactured from a shell havingseveral different density level layers, such as 241, 242, 243, and 244shown in FIG. 14. The detailed parameters can be calculated based onappropriate algorithms, such as by using the FEM tool of ANSYS software,which are not described here.

In other embodiments, when the shell 24 is designed to include severaldifferent density level layers, each layer may also include differentdensity level parts based on the material of the shell 24, the HIPprocess, and other related parameters. FIG. 15 shows an exemplaryembodiment of a target object 20 manufactured by the EBM process. Theshell 24 of the target object 20 of FIG. 15 includes three layers 241,242, and 243. The density level of the first layer 241 is about 100%.The second layer 242 include two density level parts 2421 and 2422, thefirst part 2421 is in the middle of each side of the second layer 242.As an example, the density level of the first part 2421 is about 100%;the density level of the second part 2422 is about 90%. Namely, thedensity level of the first part 2421 is greater than the second part2422. Similarly, the third layer 243 may include a first part 2431 withabout 90% density level, and a second part 2432 with about 80% densitylevel. The above parameters' arrangement is calculated in the step 74 ofthe method 70 as mentioned above.

In other embodiments, compared with the embodiment shown in FIG. 16, theshell 24 may further include some support ribs 27 extended from insidesurfaces to opposite insides surfaces of the shell 24. These supportribs 27 may also be manufactured by using the electron beam 112 to meltthe corresponding part of the powder 142 according to athree-dimensional model having support ribs. In other embodiments, theshell 24 containing powder 142 may be designed in different typesaccording to related parameters, but not limited as in the embodimentsdisclosed above.

With respect to FIG. 17, in another embodiment, method for manufacturinga target object includes forming a porous object 300 from a loose powderto have a first density level, which may be at least approximately 30%and may be more than approximately 50% in other embodiments. In theembodiment shown, the density level of the porous object 300 isapproximately 70%. In order to form the porous, or “pre-compacted”object 300, an amount of loose powder may be directed into aconstriction die (not shown) and densified to the first density level.The loose powder may be an elemental, blended elemental that may containmaster alloy, or alloy powder metallurgical product. In a preferredembodiment, an outer surface region 302 of the porous object has asurface porosity having finely distributed pores. The pores may havesizes between approximately 10 micrometers and approximately 100micrometers, which, as understood in the art, depends on the size of thepowder metallurgical products and the density level of the object. Inorder to increase the density level of a portion of object, the porousobject 300 is treated to thereby define a treated region 304 having asecond density level. More specifically, an outer surface region 302 istreated to have the second density level. As described herein, “outersurface region” is meant to describe a region of the object beginning atthe outer surface and traversing inward of the body of the object towardan imaginary axis thereof. Moreover, when referring to “outer surfaceregion” herein, such a term encompasses the whole of the outer surfaceregion 302 as disclosed above or, alternatively, only a portion thereof.Therefore, in one embodiment, the treated region 304 may encompass allor part of the outer surface region 302. Alternatively, the treatedregion 304 may be located at other parts of the object 300.

In at least one embodiment, once the outer surface region 302 istreated, the density level of the treated region 304, or the seconddensity level, is at least about 95% such that the pores that existedprior to the treatment are substantially eliminated. With a densitylevel of at least about 95% and a thickness between approximately 0.025mm and approximately 1 mm, the treated region 304 essentially acts as ahermetic seal to the inner portion 306, which still has the firstdensity level. The thickness of the treated region 304 is sufficientsuch that a seal can be formed and that sufficient strength is presentto maintain the seal through further transportation, treatment, andprocessing, such as by HIP or PIF, or any other treatment processes ormethods by which an object may be densified or consolidated. Once theporous object 300 is treated, the object 300 is densified orconsolidated to form the target object 308 having at least about 95%density level and preferably about 100% density. Notably, the shrinkageof the target object 308 after the HIP or PIF process will be taken intoaccount in a same or similar manner as described above with respect tothe other embodiment. It will be appreciated that the size and shapedifference that the target object 308 may possess relative to the porousobject 300 after HIP or PIF treatment, but before shrinkage occurs, isnot shown. It will also be appreciated that while the inner, untreatedregion 306 may include the first density level and the treated region304 may include the second density level, there may not be an exactpoint of delineation between the first and second densities. Rather,there may be a gradual change, or density gradient, from the seconddensity level to the first density level.

Such an approach of essentially sealing the porous object 300 preventsenvironmental and contaminant sources from infiltrating the porousobject 300 prior to consolidation or densification of the object 300 toa target object shape and size. Moreover, the approach as disclosedherein allows for the use of lower packing density level materials. Itwill be appreciated that the treated region 304 is essentially an insitu can that likely does not require the use of a can described herein,as is a typical practice in the art. Finally, since no can is required,machining the target object 308 after densification to remove the excessmaterial (caused by the interaction between the object and the can) isunnecessary, thereby saving time and reducing yield loss. Further costsavings are realized when it is considered that rather than replacingwell-known processes with new processes to create densified targetobjects, the disclosure herein teaches an approach that is supplementalto existing powder metallurgy processes such as HIP or PIF.

In one embodiment, treating the porous object 300 includes utilizing amaterial fusion process. In order to effectuate treatment of the outersurface region 302, a penetration of the fusion process is limited to acertain depth such that only the outer surface region 302 is treated.Such material fusion processes may include, but are not limited to,microwave, laser melting, electron beam (EB) melting, TIG melting,infrared heating, and other weld-overlay type processes involving arastered scan of the surface that produce overlapping fusion zones and ahigh quality surface layer. The local fusion layer may also be formed byprocesses including, but not limited to, transient liquid phasesintering and induction melting.

In another embodiment, treating the porous object 300 involves solidstate processing by sintering and diffusion in the outer surface region302. Such processes include, but are not limited to, microwavesintering, induction sintering, and controlled laser sintering. In yetanother embodiment, treating the porous object 300 includes formation ofa local fusion layer at the outer surface region 302.

In yet another embodiment, treating the porous object 300 includesselectively mechanically and plastically deforming the outer surfaceregion 302. The deformation may be accomplished by processes including,but not limited to peening, burnishing, cold extrusion, warm extrusion,or other deformation processes whereby the outer surface portion 302 isdeformed such that the density level thereof is at least about 95%.

In yet another embodiment, treating the porous object 300 includescoating the outer surface region 302 with a coating layer. Preferably,the coating layer is non-reactive with the materials from which theporous object 300 is made. Such a non-reactive material may includeglass or aluminum. Alternatively, a material that reacts with thesurface to form a stable coating layer that is capable of transferring aload at temperatures of approximately ½ of the melting temperature ofthe material from which the porous object is made or higher when itdiffuses into or with the base material, may be used. The coating layermay coat the entire outer surface region 302 or, alternatively, only aportion thereof.

In yet another embodiment, treating the porous object 300 includescladding-type processes. Such cladding-type processes include, but arenot limited to, laser cladding, TIG overlay, braze foil cladding, coldspray, metal paint, etc. Optionally, once the cladding-type processtakes place, the outer surface region 302 may be optionally thermallytreated to diffuse together the powder metallurgy product with thecladding-type materials in a controlled fashion in order to form analternative coating layer. In another embodiment, referring to FIG. 18,treating a porous object 400, and specifically, treating a surfaceregion 401 includes encapsulating the porous object 400 in a bag 402,made out of rubber, silicone, elastomer, or other similar material. Theporous object 400 and the bag 402 are evacuated whereby they aresubjected to a vacuum process. The porous object 400 and the bag 402 arethen heated to an elevated temperature for a period of time such thatthe bag 402 and the outer surface region 401 of the porous object 400reach the elevated temperature, but the inner portion 403 of the porousobject 400 is at a temperature below the elevated temperature (i.e., atroom temperature). In one embodiment, the elevated temperature isbetween approximately 600° F. and approximately 700° F. Once the porousobject 400 is heated as just described, the heated porous object 400 issubjected to a PIF process. Because the flow stress of the heatedsurface region 401 is lower than the flow stress of the cooler innerportion, the PIF process results in only densification of the surfaceregion 401. Similar to other embodiments, after the outer surface region401 is treated, a shell 404 is formed. The density of the shell 404 isat least approximately 95% such that the shell 404 provides a hermeticseal for the inner, untreated region 406, which has a density of atleast approximately 30%. As before, there may be a density gradientbetween the treated region (shell 404) and the untreated inner region406. Once the outer surface region 401 is treated, such that a shell 404is formed, essentially forming an in situ can, the object 400 may bedensified according to processes such as HIP, PIF, or other processes.For example, in a PIF process, the object 400 may be heated up to anelevated temperature which is a function of the melting point of thematerial(s) of which the object is composed. The object 400 is thenremoved from the source of heat and subjected to pressure betweenapproximately 5,000 psi and 60,000 psi to densify the porous object 400to a density of at least approximately 95%, and preferably 100% density,such that a target object 408 is formed.

In any of the embodiments described herein, HIP processing may beperformed at pressures in the range of up to about 45 ksi and attemperatures above about one half of the melting temperature but belowthe solidus of the material being subjected to HIP. Othermaterial-specific considerations may also further limit the range of HIPtemperatures used and therefore the HIP processing is not limited to thepressures and temperatures described herein. PIF conditions may be inthe range of about 10 ksi to up to about 60 ksi pressure and preheattemperatures above about one half of the melting temperature but belowthe solidus of the material being subjected to the PIF process. Similarmaterial-specific considerations may also further limit the range of PIFtemperatures used and therefore the pressures and preheat temperaturesdescribed herein with respect to PIF are not meant to be limiting.

The disclosure described herein may be used in combination with otherprocessing techniques including those disclosed in U.S. Pat. Nos.6,737,017, 7,329,381, and 7,897,103, which are incorporated herein byreference, in their entireties. The disclosure as described herein isparticularly useful for the consolidation of high quality titanium alloymaterials but is also applicable to other material systems including Al,Fe, Ni, Co, Mg, and other combinations of materials. The process asdisclosed herein, which essentially creates a seal on the outer surfaceregion 302 of a porous object 300, (also referred to herein as a“precompacted shape”) of loose powder material (elemental, blendedelemental that may contain master alloy, or alloy) that maintains itsown shape on all sides without the use of a container such as a can. Theprecompacted shape may be any shape including a cylinder, rectangularprism, hexagonal cylinder, or other three-dimensional shape that isappropriate for downstream consolidation and use. The process can beapplied to mill products (bars, billets, plate, sheets, tube, pipe,etc.) that can be further processed into components or to net or nearnet shape components directly. Components of interest include turbineengine parts such as disks, rings, blisks, shafts, blades, vanes, cases,tubes, and other components; automotive components including engine andbody parts; industrial components; biomedical articles; sporting goods;and other applications. These embodiments of the invention, however, arenot limited to specific applications.

In each of the embodiments, the shell may be selected to be either thinor thick, have an abrupt interface with the material internal to theshell or have a graded density interface, may be made from the samematerial as the powder being consolidated or made from a differingmaterial, the shell may be maintained in the final industrial part ormay be removed by conventional machining or other dissolution or etchingprocesses. Furthermore, the shell may contain an integral duct which canbe used to evacuate the internal cavity of the initial object and thensealed off prior to densification processing in order to enable removalof undesirable gaseous species from the internal portions of the bulkmaterial prior to densification. Additionally densified articlesproduced by this method can be net shape, near net shape, or may requiresignificant additional processing by forging, machining and/or otherprocessing routes prior to use. Preferably the article is formed of ametallic material and more preferably of a metallic alloy material butthe scope of this disclosure is not so limited.

While the technology has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the claimedinventions. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the disclosurewithout departing from the scope of the claimed invention. Therefore, itis intended that the claimed inventions not be limited to the particularembodiments disclosed, but that the claimed inventions include allembodiments falling within the scope of the appended claims.

It is to be understood that not necessarily all such objects oradvantages described above may be achieved in accordance with anyparticular embodiment. Thus, for example, those skilled in the art willrecognize that the systems and techniques described herein may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught herein without necessarilyachieving other objects or advantages as may be taught or suggestedherein.

What is claimed is:
 1. A method for manufacturing a target object, themethod comprising: forming a shell containing powder and/or a sinteredsupporting pattern using an electron beam melting (EBM) technology, theshell comprising a densified and sealed enclosure corresponding to atarget object, and the shell having a compensated shape that has avolume exceeding that of the target object; and subjecting the shellcontaining the powder and/or the sintered supporting pattern to a hotisostatic pressing (HIP) treatment or a pneumatic isostatic forging(PIF) treatment, the HIP treatment or the PIF treatment conforming thecompensated shape to an expected shape of the target object andmetallurgically bonding the shell to the powder and/or the sinteredsupport pattern within the sealed enclosure, thereby forming the targetobject{circumflex over ( )} wherein the shell comprises an outermostlayer, the outermost layer having a density level of greater than 95%:and wherein the shell comprises at least two layers, and the densitylevels of the at least two layers gradually reduce from outside toinside.
 2. The method according to claim 1, further comprising: (A)storing an original three-dimensional space model, wherein the originalthree-dimensional space model and the target object are in the sameshape; (B) analyzing a shape change of the shell expected from the HIPtreatment or the PIF treatment; and (C) calculating a compensatedthree-dimensional space model based at least in part on the shapechange, the compensated three-dimensional space model corresponding tothe compensated shape.
 3. The method according to claim 1, whereinforming the shell comprises: forming an enclosure comprising an airwaytube extending therefrom; connecting the airway tube to anair-extracting apparatus; extracting gas from the enclosure so as toform a vacuum within the enclosure; and sealing the enclosure so as toform the sealed enclosure.
 4. The method according to claim 1, furthercomprising: selectively mechanically and plastically deforming an outersurface of the shell prior to subjecting the shell to the HIP treatmentor the PIF treatment.
 5. The method according to claim 4, whereinselectively mechanically and plastically deforming comprises peening,burnishing, cold extrusion, or warm extrusion.
 6. The method accordingto claim 1, comprising performing the PIF treatment.
 7. The methodaccording to claim 1, wherein the at least two layers comprises one ormore internal layers, at least one of the internal layers comprising acentral section and a side section, the central section having a densitylevel greater than the side section.
 8. The method according to claim 1,comprising: forming the sintered supporting pattern using the EBMtechnology.
 9. The method according to claim 1, comprising performingthe HIP treatment.
 10. The method according to claim 1, wherein thetarget object comprises a turbine engine part.
 11. The method accordingto claim 10, wherein the turbine engine part comprises a disk, a ring, ablisk, a shaft, a blade, a vane, a case, or a tube.
 12. The methodaccording to claim 1, comprising: concurrently forming a plurality oftarget objects according to the method of claim.